Non-essential amino acids attenuate apoptosis of gastric cancer cells induced by glucose starvation.

ABSTRACT

Energy and nutrition are essential requirements for all living cells, including cancer cells. In the initiating stage of cancer in organs, cancer cells grow fast and have inadequate supplies of glucose, oxygen and other nutrients due to deficient angiogenesis. Anaerobic conditions cause cancer cells to rely on glycolysis, which produces pyruvate and ATP that can be used by cancer cells to survive. However, glucose starvation may result in apoptosis or necrosis of cancer cells. It has been reported that autophagy is a consequence of glucose starvation and that amino acids are products of autophagy. The present study investigated whether amino acids may represent an alternative energy source for cancer cells undergoing glucose starvation. With non-essential amino acids, growth inhibition and apoptosis of gastric cancer cells induced by glucose starvation were attenuated compared with that of cells undergoing glucose starvation without amino acids, as measured by cell viability, apoptosis rates, membrane potential of mitochondria, and apoptosis-related genes. Meanwhile, both mitochondrial DNA copy number and amino acid transporter genes were increased compared with those in control cells. Non-essential amino acids prevented gastric cancer cells from glucose starvation-induced apoptosis.